EP-4741785-A1 - TEMPERATURE SAMPLING CIRCUIT AND TEMPERATURE DETECTION METHOD

EP4741785A1EP 4741785 A1EP4741785 A1EP 4741785A1EP-4741785-A1

Abstract

The present disclosure provides a temperature sampling circuit and a temperature detection method used in a power conversion system. The temperature sampling circuit includes: a thermistor; an adjustable reference resistance module connected to the thermistor, the adjustable reference resistance module has multiple stages of different reference resistance values, and the reference resistance values of different stages corresponding to different preset sampling voltage ranges; a sampling circuit connected to the thermistor to obtain a sampling voltage value; a control circuit connected to the sampling circuit output terminal to receive the sampling voltage value and further connected to the adjustable reference resistance module. The control circuit is configured to determine a resistance value of the thermistor when the sampling voltage value meets the preset sampling voltage range of the reference resistance value of the current stage. The control circuit is further configured to switch to another stage with a different reference resistance value of when the sampling voltage value does not meet the preset sampling voltage range of the reference resistance value of the current stage, so that the newly obtained sampling voltage value meets the preset sampling voltage range of the reference resistance value of the new stage, thereby improving the temperature sampling accuracy within the full temperature range.

Inventors

XIAO, Qi
TAN, YAOSHEN
ZHANG, LUHUA

Assignees

ZHEJIANG JINKO ENERGY STORAGE CO., LTD.

Dates

Publication Date: 20260513
Application Date: 20250224

Claims (15)

A temperature sampling circuit, applied in a power conversion system, characterized in that , the temperature sampling circuit comprises: a thermistor (1) having a first terminal (11) and a second terminal (12), wherein the first terminal (11) is configured to be connected to a power supply voltage, and the second terminal (12) is configured to be grounded; an adjustable reference resistor module (2) connected to at least one of the first terminal (11) and the second terminal (12), wherein the adjustable reference resistor module (2) has a plurality of stages of different reference resistance values, and the reference resistance values of different stages correspond to different preset sampling voltage ranges; a sampling circuit (3) having a sampling terminal and a sampling circuit output terminal, wherein the sampling terminal is connected to at least one of the first terminal (11) and the second terminal (12) to obtain a sampling voltage value; and a control circuit (4) having a control circuit input terminal and a control circuit output terminal, wherein the control circuit input terminal is connected to the sampling circuit output terminal to receive the sampling voltage value, and the control circuit output terminal is connected to the adjustable reference resistor module (2); the control circuit (4) is configured to determine a resistance value of the thermistor (1) based on the sampling voltage value in response to the sampling voltage value falling within a preset sampling voltage range corresponding to a reference resistance value of the current stage, and the control circuit (4) is further configured to switch to another stage with a different reference resistance value in response to the sampling voltage value not falling within a preset sampling voltage range corresponding to a reference resistance value of the current stage, so that a newly obtained sampling voltage value falls within a preset sampling voltage range corresponding to the reference resistance value of the stage after switching.
The temperature sampling circuit according to claim 1, characterized in that , the adjustable reference resistor module (2) comprises a stage controller (21) and a plurality of reference resistors (22) with different resistance values, the stage controller (21) is connected to at least one of the first terminal (11) and the second terminal (12); and the stage controller (21) is further connected to the control circuit output terminal, the control circuit output terminal is configured to send a control signal to the stage controller (21) to control one of the plurality of reference resistors (22) with a corresponding resistance value to be connected in series with the thermistor (1).
The temperature sampling circuit according to claim 1, characterized in that , the sampling circuit (3) comprises an analog-to-digital converter, ADC, module, the ADC module has an ADC module input terminal and an ADC module output terminal, the sampling terminal is the ADC module input terminal, and the sampling circuit output terminal is the ADC module output terminal.
The temperature sampling circuit according to claim 1, characterized in that , the temperature sampling circuit comprises one adjustable reference resistor module (2); and when the adjustable reference resistor module (2) is connected to the first terminal (11), the sampling terminal is connected to the first terminal (11), or when the adjustable reference resistor module (2) is connected to the second terminal (12), the sampling terminal is connected to the second terminal (12).
The temperature sampling circuit according to claim 1, characterized in that , the temperature sampling circuit comprises two adjustable reference resistor modules (2), one of the two adjustable reference resistor modules (2) is connected to the first terminal (11), and the other one of the two adjustable reference resistor modules (2) is connected to the second terminal (12); and the sampling terminal is connected to at least one of the first terminal (11) and the second terminal (12).
The temperature sampling circuit according to claim 2, characterized in that , the adjustable reference resistor module (2) comprises a first adjustable reference resistor module (2a) and a second adjustable reference resistor module (2b), one of the first adjustable reference resistor module (2a) and the second adjustable reference resistor module (2b) is connected to the first terminal (11), and the other one of the first adjustable reference resistor module (2a) and the second adjustable reference resistor module (2b) is connected to the second terminal (12); the first adjustable reference resistor module (2a) and the second adjustable reference resistor module (2b) are respectively connected to the control circuit output terminal, such that the control circuit output terminal is capable of respectively sending control signals to the first adjustable reference resistor module (2a) and the second adjustable reference resistor module (2b); the first adjustable reference resistor module (2a) comprises N first reference sub-resistors (22a) with different resistance values, where N≥2 and N is an integer; and the second adjustable reference resistor module (2b) comprises M second reference sub-resistors (22b) with different resistance values, where M≥2 and M is an integer.
The temperature sampling circuit according to claim 6, characterized in that , one of the first adjustable reference resistor module (2a) and the second adjustable reference resistor module (2b) is a coarse-adjustment module, and the other one of the first adjustable reference resistor module (2a) and the second adjustable reference resistor module (2b) is a fine-adjustment module.
The temperature sampling circuit according to claim 7, characterized in that , the coarse-adjustment module has a greater resistance value difference between adjacent reference sub-resistors than the fine-adjustment module.
The temperature sampling circuit according to any one of claims 1-8, characterized in that , resistance values of the plurality of stages progressively increase or decrease.
A power conversion system, comprising the temperature sampling circuit according to any one of claims 1-9.
A temperature detection method, applied in temperature detection of a power conversion system by a temperature sampling circuit, the temperature sampling circuit comprises a thermistor (1), an adjustable reference resistor module (2), a sampling circuit (3), and a control circuit (4), the adjustable reference resistor module (2) has a plurality of stages of different reference resistance values, and the reference resistance values of different stages correspond to different preset sampling voltage ranges, characterized in that , the temperature detection method comprises: selecting a stage with a reference resistance value; obtaining, by the sampling circuit (3), a sampling voltage value at a sampling point under the current stage; transmitting the sampling voltage value to the control circuit (4); determining, by the control circuit (4), the sampling voltage value: when the sampling voltage value falls within a preset sampling voltage range corresponding to the reference resistance value of the current stage, determining a resistance value of the thermistor (1) based on the sampling voltage value, and obtaining a current ambient temperature value based on the resistance value of the thermistor (1), or when the sampling voltage value does not fall within the preset sampling voltage range corresponding to the reference resistance value of the current stage, switching to another stage with a different reference resistance value, obtaining a new sampling voltage value at the sampling point under the stage after switching, and continue determining the new sampling voltage value.
The temperature detection method according to claim 11, characterized in that , the switching to another stage with a different reference resistance value comprises: when the sampling voltage value exceeds an upper limit of the preset sampling voltage range corresponding to the reference resistance value of the current stage, switching to a stage with a greater reference resistance value; or when the sampling voltage value is below a lower limit of the preset sampling voltage range corresponding to the reference resistance value of the current stage, switching to a stage with a smaller reference resistance value.
The temperature detection method according to claim 11, characterized in that , the determining a resistance value of the thermistor (1) and obtaining a current ambient temperature value comprises: calculating, by the control circuit (4), the resistance value of the thermistor (1) based on the sampling voltage value; and retrieving, by the control circuit (4), a resistance-temperature comparison table of the thermistor (1), and obtaining the current ambient temperature value by looking up the table based on the resistance value of the thermistor (1).
The temperature detection method according to claim 11, characterized in that , prior to selecting a stage with a reference resistance value, the temperature detection method further comprises: determining the number of stages of the adjustable reference resistor module (2) and reference resistance values of all stages based on a range of an ambient temperature to be measured; establishing resistance-temperature comparison tables of the thermistor (1) corresponding to different stages based on temperature characteristics of the thermistor (1); and selecting a sampling point and setting preset sampling voltage ranges corresponding to reference resistance values of all stages based on actual circuit parameters of the sampling point.
The temperature detection method according to any one of claims 11-14, characterized in that , resistance values of the plurality of stages progressively increase or decrease.

Description

TECHNICAL FIELD The present disclosure relates to the field of energy storage, and in particular to a temperature sampling circuit and a temperature detection method. BACKGROUND The power conversion system (PCS) generates a large amount of heat during operation, and temperature detection is required to ensure its safety. The temperature detection can help monitor the health status of the equipment, and detect potential faults in time to prevent damage caused by overheating. Currently, in the temperature detection methods for the PCS, thermistors is usually used to measure temperature, and the ambient temperature is obtained from a lookup table based on the resistance value of the thermistor. The resistance value of the thermistor is generally measured using a resistive voltage divider, but the temperature detection accuracy still needs to be improved. SUMMARY In view of this, a temperature sampling circuit and a temperature detection method are proposed to improve accuracy of temperature detection results as compared to the related art. In a first aspect, embodiments of the present disclosure provide a temperature sampling circuit, applied in a power conversion system. The temperature sampling circuit includes: a thermistor having a first terminal and a second terminal, the first terminal is configured to be connected to a power supply voltage, and the second terminal is configured to be grounded; an adjustable reference resistance module connected to at least one of the first terminal and the second terminal, the adjustable reference resistance module has a plurality of stages of different reference resistance values, and the reference resistance values of different stages correspond to different preset sampling voltage ranges; a sampling circuit having a sampling terminal and a sampling circuit output terminal, the sampling terminal is connected to at least one of the first terminal and the second terminal to obtain a sampling voltage value; a control circuit having a control circuit input terminal and a control circuit output terminal, the control circuit input terminal is connected to the sampling circuit output terminal to receive the sampling voltage value, and the control circuit output terminal is connected to the adjustable reference resistance module. The control circuit is configured to determine a resistance value of the thermistor based on the sampling voltage value in response to the sampling voltage value falling with a preset sampling voltage range corresponding to a reference resistance value of the current stage. The control circuit is further configured to switch to another stage with a different reference resistance value in response to the sampling voltage value not falling within a preset sampling voltage range corresponding to a reference resistance value of the current stage, so that a newly obtained sampling voltage value falling within a preset sampling voltage range corresponding to the reference resistance value of the stage after switching. In one or more embodiments, the adjustable reference resistance module includes a stage controller and a plurality of reference resistors with different resistance values. The stage controller is connected to at least one of the first terminal and the second terminal. The stage controller is further connected to the control circuit output terminal, and the control circuit output terminal is configured to send a control signal to the stage controller to control one of the plurality of reference resistors with a corresponding resistance value to be connected in series with the thermistor. In one or more embodiments, the sampling circuit includes an analog-to-digital converter (ADC) module. The ADC module has an ADC module input terminal and an ADC module output terminal. The sampling terminal is the ADC module input terminal, and the sampling circuit output terminal is the ADC module output terminal. In one or more embodiments, the temperature sampling circuit includes one adjustable reference resistance module. When the adjustable reference resistance module is connected to the first terminal, the sampling terminal is connected to the first terminal; or when the adjustable reference resistance module is connected to the second terminal, the sampling terminal is connected to the second terminal. In one or more embodiments, the temperature sampling circuit includes two adjustable reference resistance modules. One of the two adjustable reference resistance modules is connected to the first terminal, and the other is connected to the second terminal. The sampling terminal is connected to at least one of the first terminal and the second terminal. In one or more embodiments, the adjustable reference resistance module includes a first adjustable reference resistance module and a second adjustable reference resistance module. One of the first adjustable reference resistance module and the second adjustable reference resistance module is connected to